drivers/firmware/google/coreboot_table.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * coreboot_table.c
   4  *
   5  * Module providing coreboot table access.
   6  *
   7  * Copyright 2017 Google Inc.
   8  * Copyright 2017 Samuel Holland <samuel@sholland.org>
   9  */
  10
  11 #include <linux/acpi.h>
  12 #include <linux/device.h>
  13 #include <linux/err.h>
  14 #include <linux/init.h>
  15 #include <linux/io.h>
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/of.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/slab.h>
  21
  22 #include "coreboot_table.h"
  23
  24 #define CB_DEV(d) container_of(d, struct coreboot_device, dev)
  25 #define CB_DRV(d) container_of(d, struct coreboot_driver, drv)
  26
  27 static int coreboot_bus_match(struct device *dev, struct device_driver *drv)
  28 {
  29         struct coreboot_device *device = CB_DEV(dev);
  30         struct coreboot_driver *driver = CB_DRV(drv);
  31
  32         return device->entry.tag == driver->tag;
  33 }
  34
  35 static int coreboot_bus_probe(struct device *dev)
  36 {
  37         int ret = -ENODEV;
  38         struct coreboot_device *device = CB_DEV(dev);
  39         struct coreboot_driver *driver = CB_DRV(dev->driver);
  40
  41         if (driver->probe)
  42                 ret = driver->probe(device);
  43
  44         return ret;
  45 }
  46
  47 static int coreboot_bus_remove(struct device *dev)
  48 {
  49         struct coreboot_device *device = CB_DEV(dev);
  50         struct coreboot_driver *driver = CB_DRV(dev->driver);
  51
  52         if (driver->remove)
  53                 driver->remove(device);
  54
  55         return 0;
  56 }
  57
  58 static struct bus_type coreboot_bus_type = {
  59         .name           = "coreboot",
  60         .match          = coreboot_bus_match,
  61         .probe          = coreboot_bus_probe,
  62         .remove         = coreboot_bus_remove,
  63 };
  64
  65 static void coreboot_device_release(struct device *dev)
  66 {
  67         struct coreboot_device *device = CB_DEV(dev);
  68
  69         kfree(device);
  70 }
  71
  72 int coreboot_driver_register(struct coreboot_driver *driver)
  73 {
  74         driver->drv.bus = &coreboot_bus_type;
  75
  76         return driver_register(&driver->drv);
  77 }
  78 EXPORT_SYMBOL(coreboot_driver_register);
  79
  80 void coreboot_driver_unregister(struct coreboot_driver *driver)
  81 {
  82         driver_unregister(&driver->drv);
  83 }
  84 EXPORT_SYMBOL(coreboot_driver_unregister);
  85
  86 static int coreboot_table_populate(struct device *dev, void *ptr)
  87 {
  88         int i, ret;
  89         void *ptr_entry;
  90         struct coreboot_device *device;
  91         struct coreboot_table_entry *entry;
  92         struct coreboot_table_header *header = ptr;
  93
  94         ptr_entry = ptr + header->header_bytes;
  95         for (i = 0; i < header->table_entries; i++) {
  96                 entry = ptr_entry;
  97
  98                 device = kzalloc(sizeof(struct device) + entry->size, GFP_KERNEL);
  99                 if (!device)
 100                         return -ENOMEM;
 101
 102                 dev_set_name(&device->dev, "coreboot%d", i);
 103                 device->dev.parent = dev;
 104                 device->dev.bus = &coreboot_bus_type;
 105                 device->dev.release = coreboot_device_release;
 106                 memcpy(&device->entry, ptr_entry, entry->size);
 107
 108                 ret = device_register(&device->dev);
 109                 if (ret) {
 110                         put_device(&device->dev);
 111                         return ret;
 112                 }
 113
 114                 ptr_entry += entry->size;
 115         }
 116
 117         return 0;
 118 }
 119
 120 static int coreboot_table_probe(struct platform_device *pdev)
 121 {
 122         resource_size_t len;
 123         struct coreboot_table_header *header;
 124         struct resource *res;
 125         struct device *dev = &pdev->dev;
 126         void *ptr;
 127         int ret;
 128
 129         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 130         if (!res)
 131                 return -EINVAL;
 132
 133         len = resource_size(res);
 134         if (!res->start || !len)
 135                 return -EINVAL;
 136
 137         /* Check just the header first to make sure things are sane */
 138         header = memremap(res->start, sizeof(*header), MEMREMAP_WB);
 139         if (!header)
 140                 return -ENOMEM;
 141
 142         len = header->header_bytes + header->table_bytes;
 143         ret = strncmp(header->signature, "LBIO", sizeof(header->signature));
 144         memunmap(header);
 145         if (ret) {
 146                 dev_warn(dev, "coreboot table missing or corrupt!\n");
 147                 return -ENODEV;
 148         }
 149
 150         ptr = memremap(res->start, len, MEMREMAP_WB);
 151         if (!ptr)
 152                 return -ENOMEM;
 153
 154         ret = bus_register(&coreboot_bus_type);
 155         if (!ret) {
 156                 ret = coreboot_table_populate(dev, ptr);
 157                 if (ret)
 158                         bus_unregister(&coreboot_bus_type);
 159         }
 160         memunmap(ptr);
 161
 162         return ret;
 163 }
 164
 165 static int __cb_dev_unregister(struct device *dev, void *dummy)
 166 {
 167         device_unregister(dev);
 168         return 0;
 169 }
 170
 171 static int coreboot_table_remove(struct platform_device *pdev)
 172 {
 173         bus_for_each_dev(&coreboot_bus_type, NULL, NULL, __cb_dev_unregister);
 174         bus_unregister(&coreboot_bus_type);
 175         return 0;
 176 }
 177
 178 #ifdef CONFIG_ACPI
 179 static const struct acpi_device_id cros_coreboot_acpi_match[] = {
 180         { "GOOGCB00", 0 },
 181         { "BOOT0000", 0 },
 182         { }
 183 };
 184 MODULE_DEVICE_TABLE(acpi, cros_coreboot_acpi_match);
 185 #endif
 186
 187 #ifdef CONFIG_OF
 188 static const struct of_device_id coreboot_of_match[] = {
 189         { .compatible = "coreboot" },
 190         {}
 191 };
 192 MODULE_DEVICE_TABLE(of, coreboot_of_match);
 193 #endif
 194
 195 static struct platform_driver coreboot_table_driver = {
 196         .probe = coreboot_table_probe,
 197         .remove = coreboot_table_remove,
 198         .driver = {
 199                 .name = "coreboot_table",
 200                 .acpi_match_table = ACPI_PTR(cros_coreboot_acpi_match),
 201                 .of_match_table = of_match_ptr(coreboot_of_match),
 202         },
 203 };
 204 module_platform_driver(coreboot_table_driver);
 205 MODULE_AUTHOR("Google, Inc.");
 206 MODULE_LICENSE("GPL");